The present application claims the priority of commonly owned copending German patent application Serial No. 100 19 550.4 filed Apr. 20, 2000. The disclosure of the above-referenced German patent application, as well as that of each US and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
The invention relates to clutches in general, particularly to improvements in friction clutches of the type suitable for use in the power trains of motor vehicles, e.g., to transmit torque between the rotary output element of a prime mover (such as the output shaft of a combustion engine, of an electric motor or of a hybrid engine) and the input shaft of a manually shiftable, automated or automatic change-speed transmission. Still more particularly, the invention relates to improvements in clutches wherein the clutch disc (also called clutch plate) comprises at least one rotary input section and an output section which is coaxial with and can be connected or is connected with the input section when one of such sections is to transmit torque to or receive torque from the other section or sections.
In certain clutches, the input and output sections of the clutch disc are permanently connected (e.g., of one piece) with each other. However, it is also known to utilize input and output sections which are separately produced parts. Still further, it is known to construct and assemble the clutches in such a way that the clutch disc does not employ or comprise a torsion damper which serves to transmit torque in the circumferential direction of the clutch disc (e.g., between the rotary output element of an engine and the input element of the transmission in the power train of a motor vehicle. Clutches employing such clutch discs and torsion dampers are disclosed, for example, in published German patent applications Ser. Nos. 2951 573, 4117 582 and 4322 578.
The clutches and/or clutch discs which embody the present invention can be, and preferably are, constructed and assembled in such a way that they can operate without the aforediscussed torsion dampers. In lieu of employing or cooperating with a torsion damper, clutch discs which embody or form part of the present invention are or can be designed to be utilized in friction clutches employing so called composite (multiple-component) flywheels which include one or more rotary oscillation dampers. Such dampers can be installed to eliminate or to reduce to a bearable value rotary oscillations of the type generated by an internal combustion engine, i.e., to enhance the comfort of the passenger(s) in a motor vehicle.
A drawback of presently known proposals to enhance the comfort offered to the passenger(s) by a motor vehicle wherein the clutch in the power train employs a one-piece clutch plate or clutch disc or a rigid or essentially rigid composite clutch disc is that the friction clutch tends to perform a so-called grabbing action under certain operating conditions of the motor vehicle, for example, in response to engagement of the friction clutch. The grabbing action (also known as frictional oscillations) causes the development of oscillations in the power train of the motor vehicle. A grabbing action which develops between the exposed surfaces of friction linings on the clutch disc and the friction surfaces which contact the friction linings (such as the friction surfaces of the pressure plate and the counterpressure plate (flywheel) of a friction clutch) frequently occurs and is particularly undesirable during starting of the motor vehicle.
An object of the present invention is to provide a novel and improved combination of parts, including the clutch disc or clutch plate, in the power train of a motor vehicle.
Another object of this invention is to provide a novel and improved friction clutch for use in the power train of a motor vehicle.
A further object of the instant invention is to provide a novel and improved combination of parts which renders it possible to eliminate or to greatly diminish frictional oscillations between the engine and the transmission in the power train of a motor vehicle.
An additional object of the invention is to provide a novel and improved method of eliminating or weakening the aforediscussed grabbing actions of friction clutches during all or practically all stages of operation of a motor vehicle.
Still another object of the invention is to provide a novel and improved power train which is designed for use in motor vehicles and to enhance the comfort to the operator of and to the passenger(s) (if any) in a motor vehicle, even under those circumstances when a certain discomfort is unavoidable in motor vehicles employing presently known power trains.
A further object of the present invention is to provide a novel and improved method of improving power trains in motor vehicles of the type wherein the friction disc of the friction clutch does not employ or does not cooperate with a torsion damper of the type disclosed in the afore-enumerated published German patent applications.
Another object of the instant invention is to provide novel and improved torque transmitting connections between the clutch disc and a damper in the power train of a motor vehicle.
An additional object of the invention is to provide a simple, compact and efficient combination of parts which can replace groups of parts in conventional power trains to thus eliminate or at least weaken the undesirable effects of the aforediscussed grabbing action or frictional oscilations even under circumstances when such action is unavoidable in motor vehicles employing conventional power trains.
Still another object of the present invention is to provide a power train which exhibits the above-enumerated features and advantages even though it employs or can employ a simple and inexpensive (such as one-piece) clutch disc or clutch plate.
One feature of the present invention resides in the provision of a clutch or in a combination which includes a clutch, particularly a friction clutch in the power train of a motor vehicle. The combination comprises a clutch disc which is rotatable about a predetermined axis and includes at least one input section having friction linings as well as an output section coaxial with and in torque-transmitting engagement with the at least one input section. Such combination further comprises a dynamic damper having a mass, and means for transmitting torque between the mass and the clutch disc. The torque transmitting means includes (a) a rotary oscillation damper having energy storing means, and (b) a slip clutch in series with the oscillation damper.
The dynamic damper forms part, or can form part, of the clutch disc. Furthermore, the output section of the clutch disc shares, or can share, at least a majority of rotary movements of the at least one input section about the predetermined axis. The transmission of torque from the clutch disc to the mass of the dynamic damper can take place by way of the slip clutch and thereupon by way of the oscillation damper.
The output section of the clutch disc includes, or can include, a hub and the dynamic damper is or can be mounted on the hub. The at least one input section of the clutch disc can comprise a flange arranged to share rotary movements of the hub about the predetermined axis. The flange is or can be of one piece with the hub and can be arranged to extend at least substantially radially of the predetermined axis. The mounting of the flange can be such that one of its sides is adjacent and that its other side faces away from the dynamic damper.
In accordance with a presently preferred embodiment, the dynamic damper comprises a portion which is in torque-transmitting engagement with the mass, at least by way of the energy storing means. The just mentioned portion of the dynamic damper is, or can be, in torque-transmitting engagement with the at least one input section and/or with the output section of the clutch disc by way of the slip clutch. The energy storing means can comprise one or more coil springs.
The novel combination further comprises, or can further comprise, a pressure plate which is coaxial with the clutch disc and is movable in the direction of the predetermined axis toward and away from frictional engagement with the friction linings of the at least one input section of the clutch disc. Such combination can further comprise a motor-driven flywheel which is coaxial with the clutch disc and is engageable by the friction linings to rotate the clutch disc in response to frictional engagement of the friction linings by the pressure plate. As utilized in the preceding sentence of this specification, the term xe2x80x9cmotor-drivenxe2x80x9d is intended to refer to a one-piece or composite flywheel which is arranged to be driven by an electric motor, by an engine (such as the internal combustion engine of a motor vehicle), by a hybrid motor or by any other suitable prime mover.
Another feature of the present invention resides in the provision of a power train which can be utilized with advantage in a motor vehicle, e.g., in a passenger car. The improved power train comprises a prime mover having a rotary output element (such as the output shaft of a combustion engine), a transmission having a rotary input element which is coaxial with the output element, and an engageable and disengageable friction clutch. The latter includes a flywheel which is coaxial with and is arranged to be driven by the output element, and a clutch disc which is coaxial with and is arranged to rotate with the output element of the prime mover in the engaged condition of the friction clutch. The clutch disc includes at least one input section having friction linings which are engaged by and receive torque from the flywheel in the engaged condition of the clutch, and the clutch disc further includes an output section which is coaxial with and in torque transmitting engagement with the at least one input section. The friction clutch further comprises a dynamic damper and means for transmitting torque between a mass of the dynamic damper and the clutch disc. Such torque transmitting means includes a rotary oscillation damper which comprises one or more coil springs or other suitable energy storing means. A slip clutch of the torque transmitting means is in series with the oscillation damper.
The flywheel can be of the type including a first mass arranged to receive torque from the output element of the prime mover, a second mass adjacent the friction linings, and a resilient damper between the first and second masses.
A space-saving layout can be arrived at if the dynamic damper surrounds one of the input and output sections and is adjacent the other of these sections. The friction clutch of such power train can further comprise a pressure plate which surrounds the dynamic damper and urges the friction linings against the flywheel in the engaged condition of the friction clutch.
At least one section of the clutch disc is or can be movable relative to the other section axially and/or radially of the input element of the transmission.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved power train itself, however, both as to its construction and the modes of assembling and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments thereof with reference to the accompanying drawings.